I'm probably exposing my ignorance here, so be gentle with a newbie...

While fiddling with a Sketchup model of the Nautilus, I have wondered about the structure of the hull. I wanted to make something that looks like it would actually work, which means that I disregard some aspects of the novel. One example would be the trip to the bottom of the sea, which is described as reaching depths of 16,000 metres (about 52,500 feet). With the steel available in the 1860's, I assume that 1/100 of that depth would be an absolute maximum for a "real" Nautilus. Which leads me to this question:

How thick would the pressure hull of the Nautilus have to be for it to dive to about 150 metres (about 500 feet)?

And while I'm at it: What if we let our imagination run wild and assume that Nemo had access to any material that is hypothetically possible. What would be the ultimate submarine hull? (Acrylic? Ceramic? Diamond? Nanosomething?) Is there any known or theoretical material that could conceivably be used to build a submarine of 1500 tons or more that was capable of diving to the bottom of the Marianas Trench?

Ceramic composite would be the best for deep level (current state of the art). Second best would be Titanium.

Although not 1500 tons (about 2 tons), Graham Hawkes has built a sub designed to go down to the Marianas Trench. The late adventurer, Steve Fossett was funding this boat and was going to pilot it, but fate changed those plans.

The Deepflight Challenger uses Ceramic composites for the pressure hull.

I always thought that it would make sense that the Nautilus might have a double hull. In that way the outer shell could be the funky, rivet encrusted thing that know and love, but the business end of the sub, the pressure hull itself, could be cylindrical and made from some kind of magical composite at would allow the deep diving referred to in the novel. That idea also helps with the ramming aspect, as the last thing you'd want to do as captain or crew is ram another ship directly with the part of the vessel that is currently keeping you dry!

In regards to the movie, I tend to just ignore the "we're deeper than a billion feet" references and pretend that the Nautilus was basically built as well as the technologies for the time would allow. In that way, she was basically a shallow water boat, perhaps maintaining depths of less than a couple hundred feet. For Nemo's purposes of vengeance, even forty feet would have been more than sufficient. Deeper depths would render the diver suits useless anyway, so beyond driving around in the dark and murk, there would not be much point to submerging beyond 200ft or so.

How large could a vessel with a ceramic hull be? If we disregard the difficulties of building a large sub this way, what would be the physical limits to the size? I imagine the thickness and weight would eventually become an issue, as it does with steel?

@Bob the Builder:

In regards to the movie, I tend to just ignore the "we're deeper than a billion feet" references and pretend that the Nautilus was basically built as well as the technologies for the time would allow.

That's pretty much how I think, as well. There doesn't seem to be much reason for the Nautilus to go very deep - at least not deeper than it would need to get under the ice of the polar regions. Of course, no hull in the world would enable it to go to the South Pole, as described in the book...

How large could a vessel with a ceramic hull be? If we disregard the difficulties of building a large sub this way, what would be the physical limits to the size? I imagine the thickness and weight would eventually become an issue, as it does with steel?

Rustein

I don't know. I would expect it to be lighter than steel though as it's a composite, and would think that much of the bulk is made up of a fibre of some kind. I believe that the ceramic composite Graham Hawkes used was licensed to him by the U.S Navy. I'm not sure if they developed it for large boats or smaller craft, or possibly very deep diving suits.